The Atmosphere Flashcards
(16 cards)
1
Q
Density
A
- Number of molecules and how closely packed they are in a given volume of any substance
- Air density = mass of air/metres cubed
2
Q
10,000ft density =
A
73%
3
Q
Pressure
A
- The total force acting on a given area
- More dense = more molecules = more pressure (an vice versa)
4
Q
Why does temperature affect density?
A
- The energy the air molecules have
- Warm temperature = high energy
5
Q
Relationship between temperature and pressure
A
- Air heated in a contained, unable to expand, pressure rises, density remains constant
- Unconfined air, density decreases.
6
Q
Troposphere
A
- Pressure, density and (normally) temperature, decrease with altitude.
- Isothermal layer exception
7
Q
8 -10,000ft pressure and density reduced to
A
3/4 of sea level value
8
Q
18-20,000ft pressure and density reduced to
A
1/2 of sea level value
9
Q
36-40,000ft pressure and density reduced to
A
1/4 of sea level value
10
Q
ISA pressure
A
1013.25 - 1hPa per 30ft to 5000ft
11
Q
ISA temperature
A
- 15 degrees C - 1.98 degrees C per 1000Ft
12
Q
Aircraft performance
A
- Varies under atmospheric density
13
Q
Pressure Altitude
A
ISA pressure set on the altimeter.
14
Q
PA formula
A
Elevation + ((1013 - current QNH) x 30)
15
Q
DA formula
A
- PA corrected for temperature
- Difference between OAT and ISA x 120, added or subtracted to PA
16
Q
Define viscosity in relation to air.
A
- Viscosity of air increases with temperature - like most gases.
- Opposite to how liquids behave.
